Abstract
OBJECTIVE: To estimate the national prevalence of asymmetric hearing among adults through applying two distinct audiometric criteria. STUDY DESIGN: National cross-sectional survey. SETTING: Ambulatory examination centers within the National Health and Nutrition Examination Survey (NHANES). PATIENTS: Non-institutionalized adults in the United States from the 2001 to 2012 cycles of NHANES aged 20 years and older with pure tone audiometric and tympanometric data (n = 6,190). INTERVENTION: Standardized protocol for pure tone audiometry and tympanometry. MAIN OUTCOME MEASURE: Proportion of asymmetric hearing according to two distinct audiometric criteria. One criterion (American Academy of Otolaryngology-Head and Neck Surgery [AAO-HNS]) specifies asymmetry as a difference between pure tone averages (PTA) greater than 15 dB, and the other (Veterans Affairs [VA]) specifies asymmetry as a difference greater than/equal to 20 dB across two contiguous frequencies or 10 dB across three contiguous frequencies. Analyses included sampling weights to account for the epidemiologic survey's complex sampling design. RESULTS: Using a definition from the AAO-HNS, overall prevalence was 2.77 and 9.46% when calculating the PTA with 0.5 to 4 kHz and 4 to 8 kHz, respectively. In contrast, through a working definition used within the VA, overall prevalence was 25.05% across 0.5 to 8 kHz. Estimates differed across sex and age, with men and older age cohorts exhibiting higher prevalence. CONCLUSIONS: A nationally-representative sample of US adults indicates higher prevalence of asymmetric hearing among men and older adult cohorts. There is currently no standard audiometric criterion for defining asymmetry, and prevalence estimates vary markedly depending on which audiometric criteria is used. Given the potentially high prevalence of asymmetry depending on criterion, clinicians should also consider other supplementary clinical data when recommending medical referral.